Developing a robust sensor for infrared imaging bolometers.

Area of Science:

• Optics and Photonics
• Materials Science
• Sensor Technology

Background:

• Traditional infrared imaging bolometers rely on thin, fragile free-standing metal foils.
• These foils are susceptible to damage from transients and limit sensor robustness.
• Existing designs present challenges in terms of durability and performance.

Purpose of the Study:

• To develop a new type of large-area sensor for infrared imaging bolometers.
• To replace fragile metal foils with a more robust substrate material.
• To enhance the noise equivalent power density and overall performance of infrared sensors.

Main Methods:

• Developed a multi-layer coated sapphire substrate as a replacement for metal foils.
• Utilized a thin deposited metal layer as the primary radiation absorber.
• Incorporated a black, carbon-based layer for partial insulation and blackbody emission.

Main Results:

• The new sapphire-based sensor demonstrated a 6x higher noise equivalent power density compared to traditional foil sensors.
• Estimated NEPD for the sapphire sensor was 23 W/m² (5 ms exposure, 60 ms decay time).
• Traditional foil sensor had an estimated NEP of 4 W/m² (1.8 ms exposure, 420 ms decay time).

Conclusions:

• The multi-layer coated sapphire substrate offers a robust and effective alternative to fragile metal foils in infrared bolometer sensors.
• The new design shows significant improvements in noise equivalent power density, indicating enhanced sensitivity.
• Sapphire's transparency and robustness make it suitable for demanding infrared imaging applications, potentially serving as a vacuum window.